My previously filed application discloses a Fibrestone construction wherein the outer wall is mounted vertically on a foundation, and an inner wall which if desired may be an inside wall of the building, is spaced from the outer wall to provide a space between the walls into which concrete or other moldable material can be cast to provide a load bearing wall. Suitable spacers or studs interconnect the walls to hold the walls in proper spaced relation while the moldable material is introduced into the space between the walls to strengthen the walls and to form a load bearing structure capable of withstanding heavy loads.